CBG-4452 avoid checking revpos on attachments

db/attachment.go

@@ -282,7 +282,7 @@ type AttachmentCallback func(name string, digest string, knownData []byte, meta
 // The callback is told whether the attachment body is known to the database, according
 // to its digest. If the attachment isn't known, the callback can return data for it, which will
 // be added to the metadata as a "data" property.
-func (c *DatabaseCollection) ForEachStubAttachment(body Body, minRevpos int, docID string, existingDigests map[string]string, callback AttachmentCallback) error {
+func (c *DatabaseCollection) ForEachStubAttachment(body Body, docID string, existingDigests map[string]string, callback AttachmentCallback) error {
 	atts := GetBodyAttachments(body)
 	if atts == nil && body[BodyAttachments] != nil {
 		return base.HTTPErrorf(http.StatusBadRequest, "Invalid _attachments")
@@ -293,9 +293,6 @@ func (c *DatabaseCollection) ForEachStubAttachment(body Body, minRevpos int, doc
 			return base.HTTPErrorf(http.StatusBadRequest, "Invalid attachment")
 		}
 		if meta["data"] == nil {
-			if revpos, ok := base.ToInt64(meta["revpos"]); revpos < int64(minRevpos) || !ok {
-				continue
-			}
 			digest, ok := meta["digest"].(string)
 			if !ok {
 				return base.HTTPErrorf(http.StatusBadRequest, "Invalid attachment")

db/attachment_test.go

@@ -408,60 +408,52 @@ func TestForEachStubAttachmentErrors(t *testing.T) {
 	docID := "foo"
 	existingDigests := make(map[string]string)
 	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err := collection.ForEachStubAttachment(body, 1, docID, existingDigests, callback)
+	err := collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.Error(t, err, "It should throw 400 Invalid _attachments")
 	assert.Contains(t, err.Error(), strconv.Itoa(http.StatusBadRequest))
 
 	// Call ForEachStubAttachment with invalid attachment; simulates the error scenario.
 	doc = `{"_attachments": {"image1.jpeg": "", "image2.jpeg": ""}}`
 	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err = collection.ForEachStubAttachment(body, 1, docID, existingDigests, callback)
+	err = collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.Error(t, err, "It should throw 400 Invalid _attachments")
 	assert.Contains(t, err.Error(), strconv.Itoa(http.StatusBadRequest))
 
-	// Check whether the attachment iteration is getting skipped if revpos < minRevpos
-	callbackCount = 0
-	doc = `{"_attachments": {"image.jpg": {"stub":true, "revpos":1}}}`
-	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err = collection.ForEachStubAttachment(body, 2, docID, existingDigests, callback)
-	assert.NoError(t, err, "It should not throw any error")
-	assert.Equal(t, 0, callbackCount)
-
 	// Verify the attachment is getting skipped if digest is in existing set
 	callbackCount = 0
 	existingDigests["image.jpg"] = "e1a1"
 	doc = `{"_attachments": {"image.jpg": {"stub":true, "revpos":2, "digest":"e1a1"}}}`
 	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err = collection.ForEachStubAttachment(body, 2, docID, existingDigests, callback)
+	err = collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.NoError(t, err, "It should not throw any error")
 	assert.Equal(t, 0, callbackCount)
 
 	// Verify the attachment is not getting skipped if digest doesn't match existing set
 	callbackCount = 0
 	doc = `{"_attachments": {"image.jpg": {"stub":true, "revpos":2, "digest":"e1a2"}}}`
 	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err = collection.ForEachStubAttachment(body, 2, docID, existingDigests, callback)
+	err = collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.NoError(t, err, "It should not throw any error")
 	assert.Equal(t, 1, callbackCount)
 
 	// Check whether the attachment iteration is getting skipped if there is no revpos.
-	doc = `{"_attachments": {"image.jpg": {"stub":true}}}`
+	doc = `{"_attachments": {"image.jpg": {"stub":true,"digest":"e1a1"}}}`
 	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err = collection.ForEachStubAttachment(body, 2, docID, existingDigests, callback)
+	err = collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.NoError(t, err, "It should not throw any error")
 
 	// Should throw invalid attachment error is the digest is not valid string or empty.
 	doc = `{"_attachments": {"image.jpg": {"stub":true, "revpos":1, "digest":true}}}`
 	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err = collection.ForEachStubAttachment(body, 1, docID, existingDigests, callback)
+	err = collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.Error(t, err, "It should throw 400 Invalid attachments")
 	assert.Contains(t, err.Error(), strconv.Itoa(http.StatusBadRequest))
 
 	// Call ForEachStubAttachment with some bad digest value. Internally it should throw a missing
 	// document error and invoke the callback function.
 	doc = `{"_attachments": {"image.jpg": {"stub":true, "revpos":1, "digest":"9304cdd066efa64f78387e9cc9240a70527271bc"}}}`
 	assert.NoError(t, base.JSONUnmarshal([]byte(doc), &body))
-	err = collection.ForEachStubAttachment(body, 1, docID, existingDigests, callback)
+	err = collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.NoError(t, err, "It should not throw any error")
 
 	// Simulate an error from the callback function; it should return the same error from ForEachStubAttachment.
@@ -470,7 +462,7 @@ func TestForEachStubAttachmentErrors(t *testing.T) {
 	callback = func(name string, digest string, knownData []byte, meta map[string]interface{}) ([]byte, error) {
 		return nil, errors.New("Can't work with this digest value!")
 	}
-	err = collection.ForEachStubAttachment(body, 1, docID, existingDigests, callback)
+	err = collection.ForEachStubAttachment(body, docID, existingDigests, callback)
 	assert.Error(t, err, "It should throw the actual error")
 	assert.Contains(t, err.Error(), "Can't work with this digest value!")
 }

db/blip_handler.go

@@ -1128,22 +1128,18 @@ func (bh *blipHandler) processRev(rq *blip.Message, stats *processRevStats) (err
 		var currentBucketDoc *Document
 
 		// Look at attachments with revpos > the last common ancestor's
-		minRevpos := 1
 		if len(history) > 0 {
 			currentDoc, rawDoc, err := bh.collection.GetDocumentWithRaw(bh.loggingCtx, docID, DocUnmarshalSync)
 			// If we're able to obtain current doc data then we should use the common ancestor generation++ for min revpos
 			// as we will already have any attachments on the common ancestor so don't need to ask for them.
 			// Otherwise we'll have to go as far back as we can in the doc history and choose the last entry in there.
 			if err == nil {
-				commonAncestor := currentDoc.History.findAncestorFromSet(currentDoc.CurrentRev, history)
-				minRevpos, _ = ParseRevID(bh.loggingCtx, commonAncestor)
-				minRevpos++
 				rawBucketDoc = rawDoc
 				currentBucketDoc = currentDoc
-			} else {
-				minRevpos, _ = ParseRevID(bh.loggingCtx, history[len(history)-1])
 			}
 		}
+		// updatedRevPos is the revpos of the new revision, to be added to attachment metadata if needed for CBL<4.0 compatibility. revpos is no longer used by Sync Gateway.
+		updatedRevPos, _ := ParseRevID(bh.loggingCtx, revID)
 
 		// currentDigests is a map from attachment name to the current bucket doc digest,
 		// for any attachments on the incoming document that are also on the current bucket doc
@@ -1159,7 +1155,7 @@ func (bh *blipHandler) processRev(rq *blip.Message, stats *processRevStats) (err
 				if !ok {
 					// If we don't have this attachment already, ensure incoming revpos is greater than minRevPos, otherwise
 					// update to ensure it's fetched and uploaded
-					bodyAtts[name].(map[string]interface{})["revpos"], _ = ParseRevID(bh.loggingCtx, revID)
+					bodyAtts[name].(map[string]interface{})["revpos"] = updatedRevPos
 					continue
 				}
 
@@ -1190,23 +1186,18 @@ func (bh *blipHandler) processRev(rq *blip.Message, stats *processRevStats) (err
 					return base.HTTPErrorf(http.StatusBadRequest, "Invalid attachment")
 				}
 
-				incomingAttachmentRevpos, ok := base.ToInt64(incomingAttachmentMeta["revpos"])
-				if !ok {
-					return base.HTTPErrorf(http.StatusBadRequest, "Invalid attachment")
-				}
-
 				// Compare the revpos and attachment digest. If incoming revpos is less than or equal to minRevPos and
 				// digest is different we need to override the revpos and set it to the current revision to ensure
-				// the attachment is requested and stored
-				if int(incomingAttachmentRevpos) <= minRevpos && currentAttachmentDigest != incomingAttachmentDigest {
-					bodyAtts[name].(map[string]interface{})["revpos"], _ = ParseRevID(bh.loggingCtx, revID)
+				// the attachment is requested and stored. revpos provided for SG/CBL<4.0 compatibility but is no longer used by Sync Gateway.
+				if currentAttachmentDigest != incomingAttachmentDigest {
+					bodyAtts[name].(map[string]interface{})["revpos"] = updatedRevPos
 				}
 			}
 
 			body[BodyAttachments] = bodyAtts
 		}
 
-		if err := bh.downloadOrVerifyAttachments(rq.Sender, body, minRevpos, docID, currentDigests); err != nil {
+		if err := bh.downloadOrVerifyAttachments(rq.Sender, body, docID, currentDigests); err != nil {
 			base.ErrorfCtx(bh.loggingCtx, "Error during downloadOrVerifyAttachments for doc %s/%s: %v", base.UD(docID), revID, err)
 			return err
 		}
@@ -1472,8 +1463,8 @@ func (bh *blipHandler) sendProveAttachment(sender *blip.Sender, docID, name, dig
 
 // For each attachment in the revision, makes sure it's in the database, asking the client to
 // upload it if necessary. This method blocks until all the attachments have been processed.
-func (bh *blipHandler) downloadOrVerifyAttachments(sender *blip.Sender, body Body, minRevpos int, docID string, currentDigests map[string]string) error {
-	return bh.collection.ForEachStubAttachment(body, minRevpos, docID, currentDigests,
+func (bh *blipHandler) downloadOrVerifyAttachments(sender *blip.Sender, body Body, docID string, currentDigests map[string]string) error {
+	return bh.collection.ForEachStubAttachment(body, docID, currentDigests,
 		func(name string, digest string, knownData []byte, meta map[string]interface{}) ([]byte, error) {
 			// Request attachment if we don't have it
 			if knownData == nil {

rest/attachment_test.go

@@ -2344,65 +2344,6 @@ func TestPushUnknownAttachmentAsStub(t *testing.T) {
 	})
 }
 
-func TestMinRevPosWorkToAvoidUnnecessaryProveAttachment(t *testing.T) {
-	rtConfig := &RestTesterConfig{
-		GuestEnabled: true,
-		DatabaseConfig: &DatabaseConfig{
-			DbConfig: DbConfig{
-				AllowConflicts: base.BoolPtr(true),
-			},
-		},
-	}
-
-	btcRunner := NewBlipTesterClientRunner(t)
-	const docID = "doc"
-
-	btcRunner.Run(func(t *testing.T, SupportedBLIPProtocols []string) {
-		rt := NewRestTester(t, rtConfig)
-		defer rt.Close()
-
-		opts := BlipTesterClientOpts{SupportedBLIPProtocols: SupportedBLIPProtocols}
-		btc := btcRunner.NewBlipTesterClientOptsWithRT(rt, &opts)
-		defer btc.Close()
-
-		btcRunner.StartPull(btc.id)
-
-		// Write an initial rev with attachment data
-		initialVersion := btc.rt.PutDoc(docID, `{"_attachments": {"hello.txt": {"data": "aGVsbG8gd29ybGQ="}}}`)
-
-		// Replicate data to client and ensure doc arrives
-		btc.rt.WaitForPendingChanges()
-		btcRunner.WaitForVersion(btc.id, docID, initialVersion)
-
-		// Create a set of revisions before we start the replicator to ensure there's a significant amount of history to push
-		version := initialVersion
-		for i := 0; i < 25; i++ {
-			version = btcRunner.AddRev(btc.id, docID, &version, []byte(`{"update_count":`+strconv.Itoa(i)+`,"_attachments": {"hello.txt": {"revpos":1,"stub":true,"digest":"sha1-Kq5sNclPz7QV2+lfQIuc6R7oRu0="}}}`))
-		}
-
-		// Note this references revpos 1 and therefore SGW has it - Shouldn't need proveAttachment, even when we replicate it
-		proveAttachmentBefore := btc.pushReplication.replicationStats.ProveAttachment.Value()
-		btcRunner.StartPushWithOpts(btc.id, BlipTesterPushOptions{Continuous: false})
-		rt.WaitForVersion(docID, version)
-
-		proveAttachmentAfter := btc.pushReplication.replicationStats.ProveAttachment.Value()
-		assert.Equal(t, proveAttachmentBefore, proveAttachmentAfter)
-
-		// start another push to run in the background from where we last left off
-		latestSeq := btcRunner.SingleCollection(btc.id).lastSeq()
-		btcRunner.StartPushWithOpts(btc.id, BlipTesterPushOptions{Continuous: true, Since: strconv.Itoa(int(latestSeq))})
-
-		// Push another bunch of history, this time whilst a replicator is actively pushing them
-		for i := 25; i < 50; i++ {
-			version = btcRunner.AddRev(btc.id, docID, &version, []byte(`{"update_count":`+strconv.Itoa(i)+`,"_attachments": {"hello.txt": {"revpos":1,"stub":true,"digest":"sha1-Kq5sNclPz7QV2+lfQIuc6R7oRu0="}}}`))
-		}
-
-		rt.WaitForVersion(docID, version)
-		proveAttachmentAfter = btc.pushReplication.replicationStats.ProveAttachment.Value()
-		assert.Equal(t, proveAttachmentBefore, proveAttachmentAfter)
-	})
-}
-
 func TestAttachmentWithErroneousRevPos(t *testing.T) {
 	rtConfig := &RestTesterConfig{
 		GuestEnabled: true,

rest/blip_client_test.go

@@ -1560,20 +1560,13 @@ func (btcc *BlipTesterCollectionClient) sendPushMsg(msg *blip.Message) {
 	btcc.parent.pushReplication.sendMsg(msg)
 }
 
-// lastSeq returns the latest sequence number for this collection.
-func (btcc *BlipTesterCollectionClient) lastSeq() clientSeq {
-	btcc.seqLock.RLock()
-	defer btcc.seqLock.RUnlock()
-	return btcc._seqLast
-}
-
 // _nextSequence returns the next sequence number for this collection.
 func (btcc *BlipTesterCollectionClient) _nextSequence() clientSeq {
 	btcc._seqLast++
 	return btcc._seqLast
 }
 
-// _pruneVersion removes the given version from the specified doc. This is not allowed for the latest version of a document.
+// pruneVersion removes the given version from the specified doc. This is not allowed for the latest version of a document.
 func (btcc *BlipTesterCollectionClient) pruneVersion(docID string, version DocVersion) {
 	btcc.seqLock.Lock()
 	defer btcc.seqLock.Unlock()